Happy hacking with HP LEDs

Last Thursday 6.2.2014 I noticed on #helsinkihacklab irc channel some talk about happyhackingday.org and noticed it is pretty soon, the then next tuesday, and it seemed pretty interesting. I naturally decided to go and join the hacklab team.

Come tuesday I drove to Helsinki Hacklab to pick up some nice 20W LEDs and headed to Pasila with the huge bag of nearly unsorted goodness (we need a pre-prepared demo kit). At the site some friends were already assembling the nuclear reactor and told me I’m allocated a slot right next to it, so all things looked bright.

I unloaded half of the goodnessbag and started to piece together a small demo of an ethernet powered light fixture featuring a high efficiency DC/DC converter controlled by software instead of a SMPSU chip. The scope proved that a switch mode power supply without filter caps rings badly and it looked fabulous on scope screen. Adding the cap made waves look nicer but the drama was gone, so I left the cap out. The circuit looks like this: https://github.com/Ell-i/Hackathon/wiki/LED-driver-forward-control-testing except I had a 20W LED instead of that huge resistor, and C1 was nowhere to be seen.

During the set up people started to trickle in and from that point on I spent the rest of the day chatting about ELL-i control system, its story, technology and all with huge amounts of people. I had also some time to pitch the Hacklab reactor and people had a blast trying to adjust carbon rods to maintain power output. The thing smoked a lot and blew up repeatedly but as my bright LED soldiered on, I was not worried a bit.


There were supposedly some speeches in the auditorium, but nobody had any kind of schedule anywhere and I was busy chatting people up and pitching interest in embedded systems development and all that. I missed Richard Stallman, which is a shame, even though I know his message pretty well, having used Free Software and Open Source Software. I’m more on the OSS side and actually like BSD/MIT licencing more. Anyway, some other speeches I missed too, but they are local so that can be fixed. Go see windytan.com for some new old school hackery.

Anyway, all in all, a very energising day full of nice chats and interesting people, thank you and see you next year.

– Teemu

Developing together: Are you brave enough to share your innovation?

Why ELL-i community is developing open source software and hardware? We have considered alternatives and chosen open HW/SW development as the best alternative, because we believe that information is a resource which adds value to our system only when it’s openly available and distributed. Good examples of this approach are Linux, Arduino and RaspberryPi. They paved the way, ELL-i is happy to follow. In today’s world you will not get far if you are trying to hide information.

Even everyday technical devices are so complex that a single person can hardly fix them not to mention designing and building without reading a manual or receiving support from other experts. From the point of sustainability this is a huge waste of resources and at ELL-i we are willing to change it.

Think about this scenario: If your proprietary SW/HW design has a bug, you will receive customer complaints. If your open SW has a bug, the community members will compete on providing the best fix for it.

At ELL-i the community members’ knowledge is expressed in a reusable manner as open code and hardware designs. Anyone can build on top of our knowledge and start to develop systems of their own. Our working ethos is that if you find our code useful, you are willing to contribute back to our code repository. This way we are able to create a positive feedback loop and gain resources which we would not able to reach otherwise, i.e. more innovators, coders and testers building better future for all.

A single person’s innovation potential is fed but also constrained by her/his environment, expertise, and life situation and so on. The larger the development community and the total innovation potential grows, the fewer of these constraints apply for the whole development base. In addition to innovation, testing is a highly important aspect. As technical systems are growing in complexity, testing takes more and more time and resources. Tests can be automated but it is challenging to generate sensible exceptions into automated test cases. Human users automatically generate exceptions to the ways that they use the equipment. The larger the community of users is, the more thoroughly the system will be tested.

Putting together Extra-Low Voltage (ELV) systems, wireline data communication and computing power, the ELL-I community will be able to create smarter and more energy efficient systems which are more accessible to all, even for those who live on the bottom of the pyramid (BOP). This way we are enabling more sustainable future for the globe. ELL-i cooperative supports sharing via open SW/HW and also via selecting affordably priced components. ELL-i has a mission to build an ecosystem that supports more sustainable and fair growth and wellbeing globally. We invite you to innovate with us in the ELL-i community!

— Jukka


A beginner electronics maker’s journey through ELL-i Hackathon – part 2/2

This is the continuation of my journey through the ELL-i Hackathon. You can also read part 1.

Back to work, the final part was to connect the whole circuit back to the ELL-i board, to an Analog-to-Digital converter that could read the received voltage and adjust the circuit to keep it always around 12 Volts. This was the “feedback loop” and it had to receive an even lower voltage for the board to be able to read it. There were more resistors, diodes and condensers to put in the circuit, but I was lacking space. I put a new protoboard, connected some wires to make it part of the original one and kept going. After a few hours of testing, connecting things and checking with the voltmeter it seemed ready to be connected to the ELL-i. I put the cable, but nothing was happening… Where was the problem now?

I connected to the serial monitor of the ELL-i board and noticed that weird numbers were appearing, as if the cable would have been in the air. I double checked my protoboard and there I found the reason: I had inserted the cable in the wrong row, so it was indeed in the air. I changed it to the correct row on the protoboard and everything looked fine. I connected again to the ethernet cable with power, and there was no smoke. The last test was coming: I put the voltmeter and I had a steady 12 volts on the point where the Power LED had to go. All set! I finally connected the power LED, put the ethernet cable in the ELL-i and the light turned on!

Complete circuit from Hackathon

My complete circuit connected to the ELL-i board

I was able to complete the workshop with a very little background in electronics, and it was a great experience. It increased my confidence in being able to interact with the environment using a computer system, in this case a board like ELL-i and I learnt that by using power-over-ethernet solutions I can power things, like a light, with only one cable and also be able to interact with the environment through sensors and in the future also with the internet. Smart Spaces was now at my fingertips!

I had a lot of fun in the workshop, learnt many new things and met nice people, so if you have the opportunity to participate in one, don’t miss it!

A beginner electronics maker’s journey through ELL-i Hackathon – part 1/2

The ELL-i Hackathon was my first experience with the ELL-i platform, and my second experience with an Arduino-based system. I come from a software development background, so in the morning, when the Hackathon started, I had no idea about what the icons of the diagram shown below tried to tell me or how that could be represented in a protoboard. Building this and making it work was my goal for this Hackathon.

PoE LED driver schematics with low-pass filter highlighted

The circuit diagram

I first walked around the tables and found a team that was speaking in English, so I joined them. They had different levels of experience in electronics and software, so that was good as we could support each other. I started by collecting the parts for the LED driver we wanted to build, and got an ELL-i board for me. I opened the development environment that I installed and tested beforehand and wrote my first program that I found around the internet to turn on a LED. Basically, a digital output of 3.3 Volts on one pin. I remember from my previous studies that someone told me that you should not connect a LED directly to the board because the LED has almost no resistance and can burn. So you should also have a resistor, and that was pretty much all I remembered about electronics.

I also knew that something like PWM existed and it was used to turn on and off the 3.3 Volts of the pin very fast to drive servos, motors or to dim LEDs. This was important to know for the LED driver, as it basically takes the voltage down by turning on and off a transistor very fast, that is like a light switch.

LED with resistorI found among the parts available for the participants a small LED light that was already wired to a resistor, so I guessed that was what I needed. I connected the LED to the corresponding pin, the other side to ground and loaded my program….. And nothing happened… Then I remembered another thing about LEDs: They have a direction, so the long leg must go on the side of the board pin. I wired it the other way around now, turned it on and finally I had a small LED on! I was very happy of this achievement and looked at my table companions that were already building complex circuits, so after loading a new program to blink the LED on and off and seeing that it also worked, I started building the circuit.

 We had a tutorial in the morning that explained the icons of the diagrams and how the whole circuit worked, so I already had identified the pieces I needed and in what part of the diagram they had to go and what the whole idea and objective of it was. I started following the instructions to build the circuit part by part and test it, so I built the first part and it seemed to work. You should have checked it with an oscilloscope, but I never understood how to really use it, especially the portable one we had on our table, so I just checked with a voltmeter and using the small LED to see if I was getting the desired behaviour.

It was all working as expected, so now was the time for the truth. The ELL-i boards gets about 50 Volts from the ethernet port using power-over-ethernet. I was using only the power from USB of 5 volts to test that all was working, so now it was time to wire the 50 volts to my circuit and see if something burnt. While I was doing this, one of the protoboards that someone was using on my table started smoking, a resistor was blown. I was hoping that this would not happen to my circuit as I would have to start again. So, I plugged it in and… no smoke! that was good! And I put my voltmeter on the other side of the circuit and I was getting around 13 Volts, so the whole power switching thing was working! My 48 volts were down to almost 12V, that I needed to turn on the Power LED!

Now we were all hungry, so together we walked to have lunch and spoke of several things including ELL-i, Finland, other electronics projects and what each one had as a background. This was a nice break to reload energy and get to know better the people I was working with.

Continues on second part.

Turku Centre for Computer Science (TUCS) students play with their brand new bucks

Eero and I had fun today with the TUCS students, teaching them how to build buck converters. Even though we had only three hours for our lab exercise, three of the groups got so far that they were able to drive an HP LED with their buck converter designs. One group even got fancy and did some disco lights! The smiles were bright.